B.5 gnatsd environment variables

gnatsd supports the GNATSDB environment varable,
See Environment, in almost the same way as the gnats tools do.
This variable is used to determine which database to use. For a local
database, it contains the name of the database to
access. gnatsd cannot service remote databases (though it might
be interesting if it could) so the database is always assumed to be
local.

If GNATSDB is not set and the --database option is not
supplied, it is assumed that the database is local and that its name is
default.